Salem,
I bought a new 15 3500 SB Tradesman last year.
As it was going to be my DD I went with a SB which was pretty maneuverable but Ram has the shortest bed at only 6'4". I carried a small 8' Lance camper which it did ok, but I just felt it was too short to go any bigger. I also towed my 21' TH and the power was amazing.
I wanted more options to carry a larger camper as well as upsize to a 5th wheel TH.
I just picked up a 16 Ram 3500 CC Aisin 4x4 with the LB. I also upgraded to the Bighorn package. I'm not a techno guy and was fine with the more basic Tradesman, but after I got it, I really think the upgrades and options on the Bighorn are well worth the roughly $3500.
I was worried about the LB and it is a little less convienent in tight areas but nothing you don't adapt to pretty quickly. You may have to make a few more 3-4 point turns but worth the advantages.
The ride is smoother in the LB both empty and towing and you get an additional 600 lb GVW. 11,700 VS 12,300 lbs.
If you plan to use for a 5th wheel I recommend the LB. It's nice to be able to turn very short without worrying about self colliding.
With the SB, you will need a slider hitch and with the 5th wheel prep group you will need a base that connects to the pucks as well as the slider hitch. I bought the BW RVK 3600 which is a solid, well constructed simple hitch. No guessing if it's locked.
I recommend the LB.
I sometimes think I should have gone with a DRW for the stability and payload for a camper. Plus they look cool.
Also, Highly recommend the Aisin/HO power train.